Lewis is a 70-year-old retired college professor. In contrast to when he was 30, he now probably a. needs more light when reading. b. is more susceptible to catching the flu. c. has significantly fewer neural connections. d. has all of these problems.

 a) needs more light when reading.

Explanation:

According to the question, as Lewis is 70 year old, he might be experiencing general old age issues that tends to occur such as weakening of hearing power, lower eye-sight, weaker bones, low stamina and ability to perform task rapidly etc.

Therefore,Lewis might be experiencing more requirement of light while reading due to weakening of eye-sight due to aging effect.

Other options are incorrect because lower neural connection,catching flu or all the problem are not experienced by Lewis. Thus, the correct option is option(a).