What can PHE's improved app help parents do?

A．Test the calories of snacks.

B．Choose delicious snacks.

C．Know the exact content in snacks.

D．Save much money to buy snacks.

解析：C　考查细节理解。根据第三段第一句“PHE said it had also improved its app so that it could mark the content of sugar, salt and fat in food and drinks”可知，英国公共卫生部表示，他们还改进了自己的应用程序，以便能够标记食物和饮料中糖、盐和脂肪的含量；据此可知，PHE改进的应用程序能帮助父母了解零食的成分，故C项正确。

3．Which of the following can be inferred from Justine Roberts' words?

A．Most parents' former experience about snacks is practical.

B．It is easy to tell healthy snacks and unhealthy snacks apart.

C．Children only take in lots of sugar from snacks and drinks.

D．Change4Life is meaningful for parents' decisions on snacks.

解析：D　考查推理判断。根据尾段Justine Roberts所说的话“The rule of thumb from Change4Life can help parents make their decision correctly and wisely”可知，来自Change4Life的经验法则能帮助父母正确而明智地作出决定；由此可推知，Change4Life对父母在零食上作出的决定有意义，故D项正确。