Read the passage carefully and attempt the following questions.

In this passage, Gerald Durrell, the naturalist, describes his attempt to look after some baby hedgehogs when he was a young boy.

On my animal-collecting trips for zoos to various parts of the world, I have had to mother quite a number of baby animals, and I have always found it a most nerve-racking task. The first real attempt I made at being a foster-mother was to four baby hedgehogs. The female hedgehog is a very good mother. She constructs an underground nursery for her young: a circular chamber about 30 centimeters below ground-level, lined with a thick layer of dry leaves. Here she gives birth to her babies which are blind and helpless. They are covered with a thick coating of spikes, but these are white and soft, as though made of rubber. They gradually harden and tum brown when the babies are a few weeks old. When they are old enough to leave the nursery the mother leads them out and shows them how to hunt for food; they walk in line, the tail of one held in the mouth of the baby behind. The baby at the head of the column holds tight to the mother's tail with grim determination, and they move through the twilit hedgerows like a strange pricky centipede.

To a mother hedgehog the rearing of her babies seems to present no problem. But when I was suddenly presented with four blind, white, rubbery-spiked babies to rear, I was not so sure. We were living in Greece at the time, and the nest, which was about the size of a football and made of oak leaves, had been dug up by a farmer working in his fields. My first job was to feed the babies but an ordinary baby's feeding-bottle was much too large for their tiny mouths. Luckily, a friend's young daughter had a doll's feeding-bottle, and I managed to persuade her to part with it. After a time the hedgehogs took to this and thrived on a diet of diluted cow's milk.

Fill in the blank with the suitable option.

Gerald Durrell's first experience of 'mothering' baby animals was _____.

mentally strenuous

The correct answer is Option (2) → mentally strenuous

Explanation:
In the passage, Gerald Durrell mentions that he found the task of looking after baby animals to be nerve-racking. This suggests that his experience of 'mothering' baby animals was mentally strenuous.