The chromosome number per cell is 46 in:

The correct answer is Option (1) → Primary oocyte

A human body cell has 46 chromosomes (2n). A cell keeps 46 until the first meiotic division halves the number.

Option (1) Primary oocyte — Correct. The primary oocyte has entered meiosis but not finished the first division, so it is still diploid with 46 chromosomes.

Option (2) Secondary oocyte — Incorrect. It forms after the first meiotic division, so it is haploid (23 chromosomes).

Option (3) Polar body — Incorrect. The polar bodies are the small haploid cells cut off at each meiotic division.

Option (4) Ovum — Incorrect. The ovum is the haploid gamete left after the second division.

NCERT Extract:
Gametogenesis – “… Oogenesis is initiated during the embryonic development stage when a couple of million gamete mother cells (oogonia) are formed within each fetal ovary; no more oogonia are formed and added after birth. These cells start division and enter into prophase-I of the meiotic division and get temporarily arrested at that stage, called primary oocytes.”
Gametogenesis – “… The theca layer is organised into an inner theca interna and an outer theca externa. It is important to draw your attention that it is at this stage that the primary oocyte within the tertiary follicle grows in size and completes its first meiotic division. It is an unequal division resulting in the formation of a large haploid secondary oocyte and a tiny first polar body (Figure 2.8b).”