Arrange the following acids in increasing order of their acidic strengths :
HCOOH, FCH2COOH, NO2CH2COOH, ClCH2COOH
1
HCOOH < FCH2COOH < NO2CH2COOH < ClCH2COOH
2
HCOOH < NO2CH2COOH < ClCH2COOH < FCH2COOH
3
NO2CH2COOH < HCOOH < ClCH2COOH < FCH2COOH
4
HCOOH < ClCH2COOH < FCH2COOH < NO2CH2COOH