Answer:
d. Ad hominem
Step-by-step explanation:
A fallacy can be defined as a mistaken or false belief that are based on illogical arguments or reasoning.
However, a lot of people might actually think it to be true but it isn't. There are various types of fallacy, these include;
I. Black or white.
II. Non sequitur.
III. Appeal to moderation.
IV. Bandwagon.
V. Appeal to authority.
VI. Straw man.
VII. Oversimplification or hasty generalization.
VIII. Appeal to ignorance.
IX. Appeal to pity.
X. Ad hominem.
Ad hominem can be defined as a type of fallacy in which the motive, character, or some other aspect of a person is attacked rather than his or her position.
This ultimately implies that, Ad hominem is typically based on prejudices, emotions, or feelings rather than appealing to reason, intellect or substance.
In this scenario, John Bardeen's research work at the Advanced Institute for Physics has progressed so slowly that even his colleagues call him a plodder. As a result, the speaker concluded that it's prudent at present not to take seriously his current theory on how strings constitute the smallest of subatomic particles. Thus, the logical fallacy described above is an ad hominem because John's slowness in his research work is bone of contention for the speaker rather than analyzing and concentrating on his theory about strings.