Read the passage given below and answer the four questions that follow:-

Microorganisms were discovered in tiny cracks within 2-billion-year-old rock in South Africa, making it the oldest rock known to host life. This finding offers insights into Earth's early life and the search for extraterrestrial life.

Deep within Earth's crust, billions of resilient microbes survive in extreme isolation, far removed from sunlight, oxygen, and food sources, growing at a glacial pace over thousands or millions of years. Previously, the oldest microbial traces were found in 100- million-year-old seafloor sediments. However, Yohey Suzuki and his team at Tokyo University have pushed this record back by 2 billion years.

They extracted a 30-cm cylindrical rock core from the Bushveld Igneous Complex in South Africa, a 2-billion-year-old volcanic region. Upon slicing the core, they found microbial cells in tiny fractures. DNA staining and imaging with advanced microscopes confirmed the microbes were indigenous, with intact cell walls, suggesting they were active.

The researchers hypothesise that the microorganisms were carried into the rock via water shortly after its formation. Clay deposits in the fractures may have provided nutrients. These microbes, primitive in evolutionary terms, offer clues about Earth's earliest life forms and their evolution.

The study also has implications for Mars exploration. Suzuki notes similarities between the Bushveld rocks and Martian rocks, suggesting the same techniques could identify life on Mars.

"This underscores the deep subsurface as a crucial environment for microbial life," says Manuel Reinhardt from the University of Göttingen, while noting that microorganisms colonised the rocks after crack formation; the timing needs investigation.

What implication does the study have for Mars exploration?

Techniques used on Earth's rocks can help detect life in Martian subsurface rocks.

The correct answer is Option (3) → Techniques used on Earth's rocks can help detect life in Martian subsurface rocks.

The passage directly addresses the implication for Mars exploration:

"The study also has implications for Mars exploration. Suzuki notes similarities between the Bushveld rocks and Martian rocks, suggesting the same techniques could identify life on Mars."

This indicates that the methods used to find the ancient life in the South African rocks—which involved extracting cores and slicing them for analysis—could be successfully applied to search for life deep within Martian rocks. This is crucial because, like the microbes in the Bushveld Complex, any surviving life on Mars is likely to be deep underground, shielded from harsh surface radiation.