Those call option contracts whose total traded value in a given day is the highest are known as Most Active Calls of that day. Information accessible through Most Active Calls includes:

Instrument Type	The type of option contract i.e. Index Options (OPTIDX) or Stock Options (OPTSTK).
Symbol	Unique keyword denoted to a stock/index, used for trading or/and getting information about the underlying (like quotes etc).
Expiry Date	The date on which the contract automatically comes to an end.
Option Type	There are two types of options, namely, Call option or CE (gives the option buyer the right to buy) and Put Option or PE (gives the option buyer the right to sell).
Strike Price	Price at which a put option can be exercised.
No of Contracts Traded	Total number of put option contracts traded on a gven day.
Contract Value (Rs. lakhs)	The value of a single contract available for trading on a given day.
Last Traded Price (LTP)	Price at which the last trade of the underlying took place.
Open Interest	Total number of outstanding contracts in the derivatives market.
Value of Underlying	Value of the underlying for a particular contract on a given date.