Clearly, capability is an essential criteria for a profession and reservation cannot ensure capable workers. So, neither I nor III holds strong. However, making one caste more privileged than the other through reservations would hinder the objectives of a classless society. So, argument II holds strong.
7. Statement: 'Guests should be provided lunch.' - A tells B.
Clearly, mechanization would speed up the work and increase the production. So, argument I is strong enough. Argument II is vague because mechanization will only eliminate wasteful employment, not create unemployment.
This is an alternating subtraction series with the interpolation of a random number, 5, as every third number. In the subtraction series, 3 is subtracted, then 4, then 3, and so on.