The correct option is B. The rule is when one of the nouns connected by 'or' or 'nor' is plural then the verb must be plural and the plural subject should be placed next to the verb. Here, 'Surendra' is singular subject and 'his friends' is plural subject thus 'have been' is used which is plural verb. Hence, 'Have been' is the best fit according to the rule
He studied architecture,mechanics, cosmology, anatomy and geology
X+3y=-4 x+3y=-4]
y+x=0 ]multiply minus===> -y-x=0 ]===elimination x===>2y=-4 ==>y=-2 x=2
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