<prompt> In a child, one should be worried if-Stammering occurs at 3 yearsLack of Toilet control at 2.5 yearsTeeth do not erupt by 11 monthsSocial smile absent by 10 weeks  <response>: Ans. is d i.e., Social smile absent by 10 weeks o Social smile develops by 2 months About other options o Delayed eruption is usually considered when there are no teeth by approximately 13 months of age --- Nelson o Toilet control develops by 3 years when child can withhold and postpone his bowel movement --- O.P. Ghai o Stammering may occur at 3 years --- Neeraj Ahuja 